Process of reducing iron ores and other metallic oxids to the metallic state.



mg allowed to escape TBS EMILrRUcE r m-rm, or LAKEWOOD, orizo.

rnocnss or REDUCING men onus Ann ornnn METALLIC .oxrns To me M riannePatented 54,1916.

STATE.

1 167 016 Specification of Letters Patent.

No Drawing.

To all whom it-may concern: 3113c it known that I, EMIL BRUCE PRATT, acitizen of the United States, residing at Lakewood, in the county ofCuyahoga and State of Ohio, have invented new and'useful Improvements inProcesses of Reducing Iron Ores and other Metallic Oxids to the MetallicState. p

This invention relates to the process of reducing iron ores and othermetallic oxids by heating within the electric furnace said ores in thepresence of a reducing agent, and has for its objects: To render theprocess considerably cheaper at geographical locations where solidcarbon is expensive and where electrical energy is cheap. To provide aprocess for reducing finely pulver-" ized ores. To regulate the carboncontent of the resultant metal. To regulate the silicon content of theresultant metal. In the reduction of iron oxids t0 the metallic state,the process has hitherto been effected by the action of heat upon theores in the presence of a .reducing agent,'said reducing agent beingsome form of solid carbon, such as coke, charcoal, or coal, the chemicalaction being the combination of the unburned carbon with the oxygen ofthe ore at high temperatures, forming carbon monoxid and carbon dioxid,gases which pass out of the furnace, leaving the metal in the reducedstate combined with certain impurities such as carbon, silicon, sulfur,etc., most of which are obtained from the impurities in the solidcarbon.

Instead of depending upon the agency of solid carbon for the removal ofthe oxygen from the ores, I employ a gas or vapor composed chiefly ofhydrogen, such as hydrogen, natural gas, methane, ethylene, or suchother hydrocarbons as shall give to the reduced metal the desired amountof carbon content.

It may be remarked that pure hydrogen may be obtained by theelectrolysis of water and that the other element, oxygen, has acommercial value and is at present being manufactured in this way, thehydrogen beas of no value. It

, pulverized ores 'App1ieation filed December 24, 1913. Serial Ifo.808,576.

cal action ofj ny' processisbased' the strong affinity "of hydrogen foroxygen,

which transposes the oxygen from the. orell.

to the hydrogen, and the. liberated carbons if any, which is notabsorbed by the iron performs :the same function. The amount of carbonpermitted to enter the furnace by this process may b'e'ivariedfrom none(in case lime instead of limestone;

be used 'fonafiux, and purefhydrogen .be used as the reducing agent) toany desired amount.

In theredution of iron oreiin the blast, furnace, it is stated by someauthorities that the siliconnontent of the reduced iron is'derivedlargely if not entirely from the silica in the solid carbon fuel. Thisbecausebf the high temperatures necessary to reduce silica to silicon.In my process, no silica.

exists either in the fuel ,or in the reducing;

agent, and therefore whatever silicon enters the reduced iron. must comefrom the .im-'

purities in the ore or flux, and if-the terns perature of the bath bekept even and not. far above the melting point of iron, no sili-. conneed be present in the iron.

Any desired amount of silicon content may be obtained by increasing thetemperature of the bath, or by adding alloys to the charge.

In the blast furnace, the heat is developed by burning an excess amountof fuel by means of a blast of hot air under pressure. This pressure isso great. that finely divided ores are blown out of the furnace. On ac-.count of the fact that no blast is necessary in connection with theelectric furnace, and

on account of the rarefied condition of hydrogen, and carbon andhydrocarbon vapors,

at temperatures within the furnace, finely may be used in this process.These rarefied gases and vapors permeate the interstices between thefinely divided charge, especially if a slight pressure be maintainedwithin the furnace.

No special design of necessary. Almost any one of the many designs ofelectric" furnaces, either the arc and may be further remarked that thegaseous resistance, or the induction types, may be hydrocarbons aredecomposed at temperatures below the melting point of iron ore,

and that the liquid and solid hydrocarbons,

obtained from petroleum, are volatilized and decomposed at temperaturesbelow the melt ing point of iron ore. Therefore, the chem1- used,although some designs' are more effi- -cient than others.

The manner of introducing the gases into,- the furnace is a question ofefficiency and economyand is related to the cost of both a theelectricity and the gas. Th areduc1ngv electric furnace is agent may ormay not be preheated before being introduced into the furnace, but Ihave found that it is desirable to preheat the reducing agent,especially if a hydrocarbon be used for this purpose. And, indeed, theentire heat necessary for this operation may be imparted to the reducingagent rather than to the charge. A hydrocarbon 0r vaporized petroleumhas no effect as a reducer unless both it and the ore be at or above thetemperature of decomposition, and in contact at such temperatures.

I claim:

The process of reducing iron ores to the metallic state consisting ofheating said ores within a furnace to the necessary temperaregulatingthe temperature of all. parts of the charge to cause the desired amountof silicav 1n the ore and 1n the fluxmg materlal to be reduced and assilicon to combine With the iron, then withdrawing the metal from thefurnace in the desired condition.

E. BRUCE PRATT.

Witnesses R. E. CHANDLER, E. J. BRADsHAw.

